Android 5.1.1 bugs on Nexus 5

My Nexus 5 has not been the same since the update. Battery drains significantly faster. It also shuts off after playing or recording videos. The latest issue happened today: phone rebooted and started "optimizing" my installed apps just like when an OS upgrade is installed. Anybody else experiencing similar issues?

I've not had any issues after upgrading to 5.1.1 , as before every update (4.4.4 to 5.0, 5.0 to 5.1 and 5.1 to 5.1.1) I did a factory reset and then updated the software so that the update was clean. I know it was a long process but I think it's prevented a lot of issues occurring in my Nexus5.